The present invention relates to an occluding device, adapted to be inserted in a blood vessel or the like by means of a catheter structure, which carries the occluding device at its distal end, with such occluding device being detachably supported by the catheter structure. Occluding devices of the balloon type have an expandable portion, which may be expanded from its retracted condition by means of the reception therein of a fluid therein, which is supplied through the catheter and, upon completion of the expansion operation, the catheter is detached from the occluding device and withdrawn from the blood vessel, with the occluding device remaining therein to perform the desired function.
The present invention is an improvement in devices of this type illustrated in prior U.S. Pat. No. 3,834,394 granted to James Hunter and Robert Sessions on Sept. 10, 1974. Extensive studies and tests with devices such as illustrated in such patent have established the need, in addition to other desirable characteristics, for maximum safety with respect to leakage of fluid from an inserted occlusion device and undesired deflation of the occlusion device. An occlusion device such as the type here involved will in a matter of a relatively short period of time, for example, several weeks following insertion, be substantially permanently retained at the desired location in the blood vessel, whereby deflation thereafter would have no disadvantageous effect. Tests have shown that regardless of the type of material employed in the balloon structure after a prolonged period of time, following insertion, the liquid in the balloon will eventually pass through the material of the balloon and enter the blood stream permitting the balloon to collapse. However, should a leakage take place, for example through the sealing valve mechanism of the occlusion device prior to such ultimate natural retention in the blood vessel, it would be possible for the occlusion device to travel in the blood vessel with possible serious consequences. It is therefore of extreme importance that the occluding device be of a construction that substantially completely precludes leakage in the valve mechanism associated therewith.
It also is of importance that the connection between the occluding device and the adjacent end of the catheter structure be such that the connection is completely foolproof with respect to inadvertent disconnection during the insertion operation and during the expanding operation so that the occlusion device cannot be lost from the end of the inserting catheter. At the same time, while the construction must be such that a positive and foolproof interlock is achieved, such construction also must have the corresponding feature of a sure and foolproof release action that precludes the possibility of the occluding device tending to remain attached to the catheter and thus defeating the desired purpose.
The desired efficiency and safety, with respect to the valve mechanism of the occlusion device, is achieved in the present invention by the utilization of dual successive valve structures, either of which is sufficient to provide the desired sealing action, and in which the primary valve mechanism retaining the liquid in the balloon may be of relatively heavy duty construction providing maximum sealing efficiency. The construction is such that a fluid conducting needle of the catheter may be inserted into the occlusion device to effect a positive actuation of both valve structures and simultaneously providing the safety feature that, in the absence of the proper connection of the catheter with the occlusion device, the valve structures will remain in a closed position.
The invention also is directed to a novel connecting structure between the occluding device and the adjacent distal end of the catheter structure in which the latter is provided with a collet-like head structure which is radially expandable and contractable, and which, in contracted position, is adapted to be inserted into a receiving socket provided on the proximal end of the occluding device. The fluid supply needle of the catheter, which is axially extendable from and retractable into the distal end of the catheter may then be moved to its extended position operative to effect expansion of the head into a firm, positive engagement with the socket of the occluding device, thereby preventing separation between the two, with continued extension of the needle being operable to actuate and open the valve members of the occluding device.
In use, the occluding device would be attached to the catheter structure with the catheter needle locking the elements in assembled relation, at which time the needle may be fully extended to open the valve members, and with the structure in such condition it may be inserted into the blood vessel and the occlusion device position at the desired location therein. Liquid may then be supplied through the needle to the occlusion device under sufficient pressure to provide the desired expansion of the balloon structure. The needle is then fully retracted into the catheter tube permitting the collet head to contract, whereby it may be freely withdrawn from the occlusion device by a withdrawal movement of the catheter. To assist such action, resilient means may be provided in the distal end of the catheter, operative to exert force on the socket of the occlusion device in a separating direction, whereby upon withdrawal of the needle and contraction of the collet head, such forces will provide additional separating force between the occluding device and the distal end of the catheter.
The invention further has among its objects the production of an occluding device which, in spite of its relatively extremely small size is very durable, providing excellent sealing action of the expanding liquid, and at the same time a relative simplicity in its design and production.